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Full-Text Articles in Computer Engineering

On Modeling Eavesdropping Attacks In Wireless Networks, Xuran Li, Jianlong Xu, Hong-Ning Dai, Qinglin Zhao, Chak Fong Cheang, Qiu Wang Oct 2014

On Modeling Eavesdropping Attacks In Wireless Networks, Xuran Li, Jianlong Xu, Hong-Ning Dai, Qinglin Zhao, Chak Fong Cheang, Qiu Wang

Hong-Ning Dai

This paper concerns the eavesdropping attacks from the eavesdroppers’ perspective, which is new since most of current studies consider the problem from the good nodes’ perspective. In this paper, we originally propose an analytical framework to quantify the effective area and the probability of the eavesdropping attacks. This framework enables us to theoretically evaluate the impact of node density, antenna model, and wireless channel model on the eavesdropping attacks. We verify via extensive simulations that the proposed analytical framework is very accurate. Our results show that the probability of eavesdropping attacks significantly vary, depending on the wireless environments (such as ...


Sptf: Smart Photo-Tagging Framework On Smart Phones, Hao Xu, Hong-Ning Dai, Walter Hon-Wai Lau Aug 2014

Sptf: Smart Photo-Tagging Framework On Smart Phones, Hao Xu, Hong-Ning Dai, Walter Hon-Wai Lau

Hong-Ning Dai

Smart phones, as one of the most important platforms for personal communications and mobile computing, have evolved with various embedded devices, such as cameras, Wi-Fi transceivers, Bluetooth transceivers and sensors. Specifically, the photos taken by a smart phone has the approximate or even equivalent image quality to that of a professional camera. As a result, smart phones have become the first choice for people to take photos to record their ordinary life. However, how to manage thousands of photos on a smart phone becomes a challenge. In this paper, we propose a new architecture in terms of Smart Photo-Tagging Framework ...


Multi-Channel Wireless Networks With Infrastructure Support: Capacity And Delay, Hong-Ning Dai, Raymond Chi-Wing Wong, Qinglin Zhao May 2014

Multi-Channel Wireless Networks With Infrastructure Support: Capacity And Delay, Hong-Ning Dai, Raymond Chi-Wing Wong, Qinglin Zhao

Hong-Ning Dai

No abstract provided.


Eavesdropping Attacks In Wireless Ad Hoc Networks Under A Shadow Fading Environment, Xuran Li, Hong-Ning Dai, Qinglin Zhao, Qiu Wang Dec 2013

Eavesdropping Attacks In Wireless Ad Hoc Networks Under A Shadow Fading Environment, Xuran Li, Hong-Ning Dai, Qinglin Zhao, Qiu Wang

Hong-Ning Dai

This paper concerns the eavesdropping attacks in wireless ad hoc networks under a shadow fading environment. Most of previous studies have only concentrated on protecting the confidential communications at both the transmitters and the receivers and little attention has been paid on investigating the eavesdropping behaviors done by the malicious nodes. We therefore investigate the eavesdropping success rate of eavesdroppers equipped with various antenna models under various channels conditions, such as the path loss effect and the shadow fading effect. In particular, we formulate the eavesdropping attack problem with consideration of both simplistic directional antenna models and realistic antenna models ...


An Analytical Model On Eavesdropping Attacks In Wireless Networks, Xuran Li, Hong-Ning Dai, Qinglin Zhao Dec 2013

An Analytical Model On Eavesdropping Attacks In Wireless Networks, Xuran Li, Hong-Ning Dai, Qinglin Zhao

Hong-Ning Dai

This paper concerns the eavesdropping problem from the eavesdroppers’ perspective, which is new since most of previous studies only concentrate on the good nodes. We propose an analytical framework to investigate the eavesdropping attacks, taking account into various channel conditions and antenna models. Our extensive numerical results show that the probability of eavesdropping attacks heavily depends on the shadow fading effect, the path loss effect and the antenna models; particularly, they imply that using directional antennas at eavesdroppers can increase the probability of eavesdropping attacks when the path loss effect is less notable. This study is helpful for us to ...


Connectivity Of Wireless Ad Hoc Networks: Impacts Of Antenna Models, Qiu Wang, Hong-Ning Dai, Qinglin Zhao Dec 2012

Connectivity Of Wireless Ad Hoc Networks: Impacts Of Antenna Models, Qiu Wang, Hong-Ning Dai, Qinglin Zhao

Hong-Ning Dai

This paper concerns the impact of various antenna models on the network connectivity of wireless ad hoc networks. Existing antenna models have their pros and cons in the accuracy reflecting realistic antennas and the computational complexity. We therefore propose a new directional antenna model called Approx-real to balance the accuracy against the complexity. We then run extensive simulations to compare the existing models and the Approx-real model in terms of the network connectivity. The study results show that the Approx-real model can better approximate the best accurate existing antenna models than other simplified antenna models, while introducing no high computational ...


On Busy-Tone Based Mac Protocol For Wireless Networks With Directional Antennas, Hong-Ning Dai, Kam-Wing Ng, Min-You Wu Dec 2012

On Busy-Tone Based Mac Protocol For Wireless Networks With Directional Antennas, Hong-Ning Dai, Kam-Wing Ng, Min-You Wu

Hong-Ning Dai

The application of directional antennas in wireless ad hoc networks offers numerous benefits, such as the extended communication range, the increased spatial reuse, the improved capacity and the suppressed interference. However, directional antennas can cause new location-dependent carrier sensing problems, such as new hidden terminal and deafness problems, which can severely degrade the network performance. Recently, a few schemes have been proposed to address these problems. However, most of these existing methods can only partially solve the hidden terminal and deafness problems. Some of them even bring significant performance overhead. In this paper, we propose a novel MAC protocol, in ...


Eavesdropping Security In Wireless Ad Hoc Networks With Directional Antennas, Qiu Wang, Hong-Ning Dai, Qinglin Zhao Dec 2012

Eavesdropping Security In Wireless Ad Hoc Networks With Directional Antennas, Qiu Wang, Hong-Ning Dai, Qinglin Zhao

Hong-Ning Dai

The eavesdropping security of wireless ad hoc networks has attracted considerable attention recently. However, most of current studies only consider OMN networks, where each node is mounted with a single omni-directional antenna, which radiates radio signals in all directions and consequently leads to the high eavesdropping possibility. Compared with an omnidirectional antenna, a directional antenna can concentrate the radio signals on some desired directions so that it can potentially reduce the eavesdropping possibility. This paper investigates the eavesdropping security of wireless ad hoc networks equipped with directional antennas. In particular, we study the eavesdropping possibility of OMN networks, SDA networks ...


An Overview Of Using Directional Antennas In Wireless Networks, Hong-Ning Dai, Kam-Wing Ng, Min-You Wu Dec 2012

An Overview Of Using Directional Antennas In Wireless Networks, Hong-Ning Dai, Kam-Wing Ng, Min-You Wu

Hong-Ning Dai

Compared with omni-directional antennas, directional antennas have many merits, such as lower interference, better spatial reuse, longer transmission range and the improved network capacity. Directional antennas enable numerous emerging outdoor and indoor applications, which have been addressed in many recent studies. Despite the advances in wireless networks with directional antennas (DAWNs), there are many research challenges in all layers of DAWNs. This paper presents a detailed study on recent advances and open research issues on DAWNs. Firstly, we briefly introduce the classification of directional antennas, antenna radiation patterns, antenna modes as well as the challenges in the physical layer of ...


Channel Allocation In Wireless Networks With Directional Antennas, Hong-Ning Dai, Kam-Wing Ng, Min-You Wu Dec 2012

Channel Allocation In Wireless Networks With Directional Antennas, Hong-Ning Dai, Kam-Wing Ng, Min-You Wu

Hong-Ning Dai

In this paper, we study the channel allocation in multi-channel wireless ad hoc networks with directional antennas. In particular, we investigate the problem: given a set of wireless nodes equipped with directional antennas, how many channels are needed to ensure collision-free communications? We derive the upper bounds on the number of channels, which heavily depend on the node density and the interference ratio (i.e., the ratio of the interference range to the transmission range). We construct several scenarios to examine the tightness of the derived bounds. We also take the side-lobes and back-lobes as well as the signal path ...


On Eavesdropping Attacks In Wireless Sensor Networks With Directional Antennas, Hong-Ning Dai, Qiu Wang, Dong Li, Raymond Chi-Wing Wong Dec 2012

On Eavesdropping Attacks In Wireless Sensor Networks With Directional Antennas, Hong-Ning Dai, Qiu Wang, Dong Li, Raymond Chi-Wing Wong

Hong-Ning Dai

The eavesdropping attack is a serious security threat to a wireless sensor network (WSN) since the eavesdropping attack is a prerequisite for other attacks. Conventional WSNs consist of wireless nodes equipped with omnidirectional antennas, which broadcast radio signals in all directions and are consequently prone to the eavesdropping attacks. Different from omnidirectional antennas, directional antennas radiate radio signals on desired directions and potentially reduce the possibility of the eavesdropping attacks. In this paper, we propose a model to analyze the eavesdropping probability in both single-hop WSNs and multihop WSNs with omnidirectional antennas and directional antennas. We verify the correctness of ...


On The Connectivity Of Wireless Networks With Multiple Directional Antennas, Hong-Ning Dai Dec 2011

On The Connectivity Of Wireless Networks With Multiple Directional Antennas, Hong-Ning Dai

Hong-Ning Dai

The network connectivity is one of important measures of the performance of wireless networks. However, most of current studies on the network connectivity only consider either an SOMN network, where each node is mounted with a single omni-directional antenna, or an SDA network, where each node is mounted with a single directional antenna. Using multiple directional antennas instead of a single directional antenna can potentially improve the network performance. In this paper, we investigate the connectivity of a novel network, in terms of an MDA network, where each node is mounted with multiple directional antennas. We found that MDA networks ...


Link Scheduling In Multi-Transmit-Receive Wireless Networks, Hong-Ning Dai, Soung Chang Liew, Liqun Fu Dec 2010

Link Scheduling In Multi-Transmit-Receive Wireless Networks, Hong-Ning Dai, Soung Chang Liew, Liqun Fu

Hong-Ning Dai

This paper investigates the problem of link scheduling to meet traffic demands with minimum airtime in a multitransmit-receive (MTR) wireless network. MTR networks are a new class of networks, in which each node can simultaneously transmit to a number of other nodes, or simultaneously receive from a number of other nodes. The MTR capability can be enabled by the use of multiple directional antennas or multiple channels. Potentially, MTR can boost the network capacity significantly. However, link scheduling that makes full use of the MTR capability must be in place before this can happen. We show that optimal link scheduling ...


Exploring Security Improvement Of Wireless Networks With Directional Antennas, Hong-Ning Dai, Dong Li, Raymond Chi-Wing Wong Dec 2010

Exploring Security Improvement Of Wireless Networks With Directional Antennas, Hong-Ning Dai, Dong Li, Raymond Chi-Wing Wong

Hong-Ning Dai

There are a number of studies on using directional antennas in wireless networks. Many of them concentrate on analyzing the theoretical capacity improvement by using directional antennas. Other studies focus on designing proper Medium Access Control (MAC) protocols to improve the practical network throughput. There are few works on the security improvement using directional antennas. In this paper, we explore the benefits of directional antennas in security improvements on both singlehop and multi-hop wireless networks. In particular, we found that using directional antennas in wireless networks can significantly reduce the eavesdropping probabilities of both single-hop transmissions as well as multi-hop ...


Upper Bounds On The Number Of Channels To Ensure Collision-Free Communications In Multi-Channel Wireless Networks Using Directional Antennas, Hong-Ning Dai, Kam-Wing Ng, Min-You Wu Dec 2009

Upper Bounds On The Number Of Channels To Ensure Collision-Free Communications In Multi-Channel Wireless Networks Using Directional Antennas, Hong-Ning Dai, Kam-Wing Ng, Min-You Wu

Hong-Ning Dai

Recent studies have found that using multiple channels can separate concurrent transmissions and significantly improve network throughput. However, these studies have only considered wireless nodes that are equipped with omni-directional antennas, which have high interference. On the other hand, other researchers have found that using directional antennas in wireless networks can reduce interference and improve the network performance. But their studies have only considered single channel to be used in wireless networks with directional antennas. Thus, integrating the two technologies of multiple channels and directional antennas together can potentially bring more benefits. Some previous works have studies the capacity on ...


Throughput And Delay In Wireless Sensor Networks Using Directional Antennas, Hong-Ning Dai Dec 2008

Throughput And Delay In Wireless Sensor Networks Using Directional Antennas, Hong-Ning Dai

Hong-Ning Dai

Most of studies only consider that wireless sensor networks are equipped with only omni-directional antennas, which can cause high collisions. It is shown that the per node throughput in such networks is decreased with the increased number of nodes. Thus, the transmission with multiple short-range hops is preferred to reduce the interference. However, other studies show that the transmission delay increases with the increased number of hops.

In this paper, we consider using directional antennas in wireless sensor networks. We have found that using directional antennas not only can increase the throughput capacity but also can decrease the delay by ...


Collision-Tolerant Transmission With Narrow-Beam Antennas, Hong-Ning Dai, Kam-Wing Ng, Min-You Wu, Bo Li Oct 2008

Collision-Tolerant Transmission With Narrow-Beam Antennas, Hong-Ning Dai, Kam-Wing Ng, Min-You Wu, Bo Li

Hong-Ning Dai

The application of directional antennas in wireless ad hoc networks brings numerous benefits, such as increased spatial reuse and mitigated interference. Most MAC protocols with directional antennas are based on the RTS/CTS mechanism which works well in wireless ad hoc networks using omni-directional antennas. However, RTS/CTS frames cannot mitigate the interference completely. Besides, they also contribute a lot to the performance overhead. This paper studies the problem from a new perspective. We have found that the transmission success probability under directional transmission and directional reception is quite high when the antenna beamwidth is quite narrow. Motivated by the ...


On Collision-Tolerant Transmission With Directional Antennas, Hong-Ning Dai, Kam-Wing Ng, Min-You Wu Dec 2007

On Collision-Tolerant Transmission With Directional Antennas, Hong-Ning Dai, Kam-Wing Ng, Min-You Wu

Hong-Ning Dai

The application of directional antennas in wireless networks brings numerous benefits, such as increased spatial reuse and mitigated interferences. Most MAC protocols with directional antennas are based on the RTS/CTS mechanism which works well in wireless networks using omni-directional antennas. However, RTS/CTS frames cannot mitigate the interfering nodes completely. Besides, they also contribute a lot to the performance overhead. This paper studies the problem from a new perspective. We analyze the transmission success probability under directional transmission and directional reception when the antenna beamwidth is quite narrow. Motivated by the analytical results, we design a lightweight MAC protocol ...


On The Capacity Of Multi-Channel Wireless Networks Using Directional Antennas, Hong-Ning Dai, Kam-Wing Ng, Raymond Chi-Wing Wong, Min-You Wu Dec 2007

On The Capacity Of Multi-Channel Wireless Networks Using Directional Antennas, Hong-Ning Dai, Kam-Wing Ng, Raymond Chi-Wing Wong, Min-You Wu

Hong-Ning Dai

The capacity of wireless ad hoc networks is affected by two key factors: the interference among concurrent transmissions and the number of simultaneous transmissions on a single interface. Recent studies found that using multiple channels can separate concurrent transmissions and greatly improve network throughput. However, those studies only consider that wireless nodes are equipped with only omnidirectional antennas, which cause high collisions. On the other hand, some researchers found that directional antennas bring more benefits such as reduced interference and increased spatial reuse compared with omnidirectional antennas. But, they only focused on a single-channel network which only allows finite concurrent ...


A Busy-Tone Based Mac Scheme For Wireless Ad Hoc Networks Using Directional Antennas, Hong-Ning Dai, Kam-Wing Ng, Min-You Wu Dec 2006

A Busy-Tone Based Mac Scheme For Wireless Ad Hoc Networks Using Directional Antennas, Hong-Ning Dai, Kam-Wing Ng, Min-You Wu

Hong-Ning Dai

Applying directional antennas in wireless ad hoc networks offers numerous benefits, such as extended communication range, increased spatial reuse, improved capacity and suppressed interference. However, directional antennas can cause new location-dependent carrier sensing problems, such as new hidden terminal and deafness problems, which can cause severe penalties to the performance. Recently, a few schemes have been proposed to tackle these problems. However, these methods can provide limited solutions on the hidden terminal and deafness problems. We propose a new MAC protocol, termed the busy-tone based directional medium access control (BT-DMAC) protocol. When the transmission is in progress, the sender and ...


An Overview Of Mac Protocols With Directional Antennas In Wireless Ad Hoc Networks, Hong-Ning Dai, Kam-Wing Ng, Min-You Wu Dec 2005

An Overview Of Mac Protocols With Directional Antennas In Wireless Ad Hoc Networks, Hong-Ning Dai, Kam-Wing Ng, Min-You Wu

Hong-Ning Dai

Although directional antennas have been used in mobile communications systems for quite a long time, realistic applications of directional or smart antennas in wireless ad hoc network have emerged just in recent years. Directional antennas provide numerous benefits, such as higher gains, increased transmission range and low interferences. Wireless medium access schemes play a crucial role in ensuring the efficient and fair sharing of wireless resources. Therefore there are many research work on mechanisms at the wireless medium access layer by using directional antennas. The new features of MAC with directional antennas can cause not only location dependent carrier sensing ...